An example of a related art paper binding system (paper folding apparatus) of an image forming apparatus such as a copier is disclosed in U.S. Pat. No. 6,004,254.
The related art paper folding apparatus of an image forming apparatus will be described with reference to FIG. 1.
Referring to FIG. 1, a reference numeral 1 denotes an image forming apparatus (copier), and a reference numeral 2 denotes a paper folding apparatus.
The paper folding apparatus 2 directly ejects papers finished from the copier 1 onto a stack tray 7 by controlling an inlet flap 3 or binds the papers using a stapler unit (stapler head 18 and a stapler anvil 19), folding rollers 26 and 27, and a paper positioning unit 28 to eject them onto an eject tray 35.
The operation of folding papers ejected from the copier 1 will be described in more detail.
The papers ejected from the copier 1 move to paper guides 11 and 12 of the folding apparatus by passing through rollers 4 provided in a paper eject outlet of a main body of the copier. The papers moved to the paper guides 11 and 12 move between the stapler head 18 and the stapler anvil 19 through eject rollers 13 and 14 and then ends of the papers are aligned in a base 6 of the paper positioning unit 28.
The paper positioning unit 28 includes a paper position sensor 63 that moves the paper positioning unit in a direction of an arrow ‘a’ in accordance with a signal of the paper position sensor 63.
If the paper position sensor senses small sized papers, the paper positioning unit 28 moves to the position of the small sized papers in accordance with a sensed signal of the paper position sensor. If the paper position sensor senses big sized papers, the paper positioning unit 28 moves to the position of the big sized papers in accordance with the sensed signal of the paper position sensor.
Meanwhile, when the papers are aligned in the paper positioning unit 28, respective plate springs 5a and 5b prevent the papers from moving to the paper positioning unit. Accordingly, to facilitate movement of the papers to the paper positioning unit, the upper semi-circular roller 17 and the lower semi-circular roller 9 have an eccentric cam shape.
In other words, when the papers move to align the ends of the papers in the base 6 of the paper position unit 28, flat portions of the upper and lower semi-circular rollers face the plate springs 5a and 5b, respectively, thereby forming a space between the plate springs and the upper and lower semi-circular rollers. The space serves to facilitate movement of the papers. When the papers moved to the paper positioning unit are stapled using the stapler head 18 and the stapler anvil 19, or are folded using folding rollers 26 and 27, curved surfaces of the semi-circular rollers closely face the respective plate springs by rotating the upper and lower semi-circular rollers. Thus, the papers are supported between the semi-circular rollers and the plate springs.
The central parts of the papers supported between the semi-circular rollers 9 and 17 and the plate springs 5a and 5b are stapled by the stapler head 18 and the stapler anvil 19. The upper and lower semi-circular rollers 9 and 17 support the papers to place the stapled parts of the papers at inlets of the folding rollers 26 and 27. Then, the upper and lower semi-circular rollers 9 and 17 move at the same time.
In this state, the upper and lower semi-circular rollers are rotated in opposite directions and at the same time a knife 25a provided in a protrusion unit 25 pushes the stapled parts of the papers to the folding rollers 26 and 27. If the stapled parts are supported by the folding rollers, the papers are folded by half by means of action of the folding rollers 26 and 27 and then pushed between the folding rollers, thereby completing binding of the papers. The papers passed through the folding rollers are ejected to the eject tray 35.
Meanwhile, reference numerals 15 and 16 denote switch flaps that guide the papers passed through the eject rollers to be aligned in the paper positioning unit 28 in the order of page or ejection.
In the aforementioned related art paper binding system, the binding papers are supported by elasticity of the plate springs 5a and 5b provided at an opposite side of the upper and lower semi-circular rollers 17 and 9. Therefore, reliability in supporting the papers depends on how many papers are bound, i.e., the thickness of the binding papers.
Furthermore, since a number of the binding papers are moved by rotation of the upper and lower semi-circular rollers, the papers which are not in contact with the upper and lower semi-circular rollers may not be moved.
Moreover, as shown in FIG. 1, since a moving path of the papers is curved, desirable movement of the papers may not be carried out.